All buckled in? Downed a whiskey (or maybe several)? It’s important to be prepared, because “A Dragonfly in Amber” is a roller coaster of a finale, whipping Outlander from drama to melodrama, from the 1740s to the 1960s, and from the culmination of one romance to the precipice of another. It loop-de-loops through the deaths of several patriarchs, some metaphorical and some in grisly Technicolor. In its jam-packed 90 minutes, the finale tries to both end Outlander’s second season with a flourish and build excitement for season three. If only it were a bit more successful.

An unconventional episode calls from an unconventional recap, so let’s break down the best and worst of “Dragonfly in Amber.” We’ll start with the best stuff … and then consider the not-so-stellar.

WHAT WORKS

Jamie and ClaireThe long-dreaded day has finally arrived: Prince Charles is determined that his armies should fight the British on Culloden Moor. For begging Charles to stay his hand, Jamie is labeled a doubting Thomas by the pompous prince. For wondering whether it would be wise to poison Bonnie Charlie, he’s labeled a traitor by his uncle Dougal. It’s quite a betrayal in poor Dougal’s eyes: He just lost his brother, he’s famished, and he’s jealous that his nephew was entrusted with the guardianship of his son, Hamish. Now on top of all of that, he thinks he’s been backstabbed by that very same nephew and his nephew’s wife, of whom he had let himself grow so fond. When he charges after Jamie, he’s fighting to kill.

Instead of selecting regicide — which he and Claire should probably have done ages ago — Jamie is forced to commit pseudo-patricide. (After all, Dougal was like a father to him.) And so, it seems, Dougal’s death is the final nail in the coffin for Jamie and Claire. It’s a bad omen, in and of itself, to kill your kinsman on the day of battle. But after Rupert MacKenzie comes upon Jamie and the corpse in a compromising position, it cements the fact that our heroes will no longer find stability in 1745. For the sake of the friendship he once felt for him, Rupert agrees to give Jamie two hours before seeking vengeance. It’s clear that, once time is up, he means to make Jamie pay for his actions — unless the Redcoats get to them first.

After making provision for his men (via Murtagh) and for Lallybroch (via Fergus), Jamie takes Claire on horseback to the standing stones, where they have a tearful farewell. Claire doesn’t want to return to the 20th century, but Jamie, always so attentive to detail, has realized that Claire is two-to-three-months pregnant. Claire must go so that she can have their child; she must go to keep it safe. Our heroes have sex one last time and exchange tearful vows. Like Jack and Rose in Titanic — another high-stakes, believably smitten couple — Caitriona Balfe and Sam Heughan sell the hell out of this emotional good-bye. Their chemistry is the fulcrum of this epic. Without it, Outlander would be too heavy to lift.

Claire begs Jamie to come with her — there’s room on the door! — but Jamie refuses, so she must go back to the future alone. Well, not exactly alone. But we’ll get to Brianna shortly.

Roger’s IntroductionThe best thing that 1968 has to offer is Roger Wakefield, a.k.a. Roger MacKenzie, a.k.a. the descendant of Geillis and Dougal’s secret love child. Played by a genial, bearded Richard Rankin, Roger is a turtleneck-wearing historian from Oxford who returns to Scotland to pay his last respects to the man who raised him. Claire and Brianna have journeyed from London for the same purpose, and they end up befriending Roger. After hanging out with him for a couple of days, they soon uncover the truth about his and Brianna’s parentage.

Roger becomes a key player in Diana Gabaldon’s novels, so his casting is important, to say the least. (As always, let’s keep the comments spoiler-free for those who haven’t read the books.) In Rankin, Outlander has found an actor who comes off as intelligent and compelling, skeptical but persuadable, funny, and more attractive than your average academic has any right to be. Well done, show.

Murtagh and FergusNeither Jamie’s unflappable godfather nor his surrogate son disappoint in this finale. Though they don’t have much to do, they stay loyal until the end. And watching Claire bid her boy farewell is wrenching.

The Return of Geillis DuncanIt’s a thrill to meet Geillis again. She’s as charismatic and terrifying as ever in the form of rabble-rousing history buff Gillian Edgars, a woman determined to go back in time and help Bonnie Prince Charlie win his war. We also learn that her pesky husband-killing habits started early: Claire, Roger, and Brianna don’t make it to the standing stones in time to save poor Mr. Edgars, but they do arrive just as Gillian passes through.

Faced with indisputable evidence seen with her own eyes, Brianna finally believes. (Her previous uncertainty serves as a nice callback to Prince Charles’s admonition of Jamie; she’s the real doubting Thomas of our story.) No, her mother isn’t crazy. Her story isn’t a fairy tale. Claire did travel 200 years back in time, she did fall in love, she did get pregnant, and she did return to the 20th century to raise her daughter with a man who wasn’t the father. “It’s true, then,” she exclaims. “Everything you said is true.”

WHAT DOESN’T

BriannaI have called Outlander a uniformly well-acted show, but Brianna, as played by Sophie Skelton, is the first major cast member to inspire doubt. Though she’s striking and has presence, Skelton’s performance as Brianna is as uneven as the finale itself. To be fair, she’s given a lot to do: Brianna has to seem comfortable in 1968; she has to speak with an American accent even though everyone around her is Scottish or English; she has to appear to be Jamie Fraser’s daughter while also fighting furiously with her mother about whether that’s possible; and she has to earn our affection while acting petulant and childish. Still, Brianna left me cold, and that doesn’t bode well for the future.

The Pacing“Dragonfly in Amber” attempts to be exhaustive, but ends up exhausting. It attempts an ambitious number of tasks: It must introduce us to the uneasy mother-daughter dynamic between Brianna and Claire (who, in service to the times, seems to be channeling The Graduate’s Mrs. Robinson); set up the relationship between Brianna and Roger; reveal what Claire’s been up to in the past 20 years, so we understand what she would sacrifice should she decide to go back; and show us what happens to Lallybroch specifically and Scotland as a whole. That’s just some of the ground the finale aims to cover in its 20th-century story line.

Back in the 18th century, after weeks of buildup, we don’t even get a glimpse of the climactic battle with the British. What happened? Did the budget dry up?

Even without Culloden, it’s too much. The finale feels rushed in places, choppy in others. It certainly gets no help from a lackluster script, which isn’t able to inject much humor into the proceedings to break the tension.

Though “Dragonfly in Amber” overreaches, some elements still make for good, memorable television, and it serves as an appropriate end to a season that also suffered plenty of ups and downs. So, here’s to hoping for calmer waters in season three. There’s still plenty of time for Skelton to get her sea legs, and perhaps the show, now released from the artificial pressure of trying to change an immutable future, will get to go back to doing what it does best: instilling a costume drama with wry feminist sensibilities. I have faith. After all, blessed are those who have not seen and yet who have believed.